Married partners often diagnosed with the same psychiatric disorders, large study finds

A study of nearly 14.8 million people across Taiwan, Denmark and Sweden found that people with psychiatric disorders are more likely to marry partners who have similar mental-health conditions, and that married couples are often diagnosed with the same disorder, researchers reported.

Published in the journal Nature Human Behaviour, the cross-national analysis examined nine psychiatric diagnoses — schizophrenia, bipolar disorder, depression, anxiety disorders, attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder, obsessive-compulsive disorder (OCD), substance use disorders and anorexia nervosa — and found consistent patterns across countries and generations.

The researchers drew on registry and administrative health data to assess diagnoses and marital pairings in the three countries, which provide large, population-based samples and longitudinal records of medical encounters. The analysis identified that individuals with a given psychiatric disorder were more likely than expected by chance to be married to someone with a psychiatric disorder, and were disproportionately likely to share the same specific diagnosis as their spouse.

The pattern held for the full set of conditions studied and was observed both within and across the national samples, the authors said. The team described the finding as evidence of assortative mating by psychiatric status — a tendency for people to select partners with similar characteristics — which may be a stable feature of human relationships across cultural and temporal contexts.

The study did not report a single causal mechanism behind the observed clustering. The authors noted that multiple factors could contribute to the pattern, including partner selection based on shared experiences or social networks, mutual influence within relationships, or overlapping genetic and environmental risk factors. The observational design and reliance on recorded diagnoses mean the analysis cannot determine whether partners influence each other’s mental health, whether shared underlying risk factors lead to similar diagnoses, or some combination of both.

Researchers highlighted potential implications for public health and psychiatric research. If people with psychiatric disorders tend to partner with others who have similar conditions, that pattern could affect the aggregation of mental-health risk within families, influence estimates of heritability in genetic studies, and shape the needs of couples and their children for clinical services.

The study’s large, multi-country sample strengthens the generalizability of the findings compared with earlier, smaller studies, the authors said. National registries in Denmark and Sweden and administrative data in Taiwan allowed the team to identify diagnosed conditions and marital links over extended periods, capturing multiple generations in some cases.

The authors acknowledged limitations. Diagnoses recorded in administrative health data reflect contacts with health services and may miss undiagnosed or untreated conditions. Cultural differences in help-seeking and diagnostic practices could influence patterns in different countries, even though the overall trend was consistent. The study focused on married couples and did not examine cohabiting or nonmarried partnerships, which have become more common in some settings.

Mental-health experts who were not involved in the study said the findings underscore the importance of considering couple-level dynamics in clinical care and research, but cautioned against overinterpreting the results as evidence that marriage causes shared disorders. They recommended further research to disentangle selection effects from shared environmental and reciprocal influences within relationships.

The paper concludes that assortative mating for psychiatric disorders appears robust across nations and diagnostic categories, and that further study is warranted to clarify mechanisms and to assess how these patterns affect family risk and healthcare provision.